ios 在 UIView 中绘制矩形
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Drawing a rectangle in UIView
提问by Ashish Agarwal
I am trying to draw a transparent rectangle in my UIView which has a black border.
我想在我的 UIView 中绘制一个透明矩形，它有一个黑色边框。
My code however creates a completely black rectangle. Here's my code so far:
然而，我的代码创建了一个完全黑色的矩形。到目前为止，这是我的代码：
- (void)drawRect:(CGRect)rect
{
// Drawing code
CGRect rectangle = CGRectMake(0, 100, 320, 100);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 0.0, 0.0, 0.0, 0.5);
CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 0.5);
CGContextFillRect(context, rectangle);
}
回答by Guo Luchuan
- (void)drawRect:(CGRect)rect
{
// Drawing code
CGRect rectangle = CGRectMake(0, 100, 320, 100);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 0.0); //this is the transparent color
CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 0.5);
CGContextFillRect(context, rectangle);
CGContextStrokeRect(context, rectangle); //this will draw the border
}
the effect is like this (backgroundColor is blue)
效果是这样的（backgroundColor为蓝色）
回答by Madhu
It will provide the rectangle/square by adjusting values of self frame (customized view or subclass of any class which is inherited from UIView) with transparency.
它将通过调整UIView具有透明度的自框架（自定义视图或继承自的任何类的子类）的值来提供矩形/正方形。
[self.layer setBorderWidth:1.0];
[self.layer setBorderColor:[[UIColor colorWithRed:0.10 green:0.45 blue:0.73 alpha:1.0] CGColor]];
[self.layer setCornerRadius:2.0];
[self.layer setShadowOffset:CGSizeMake(-2, -2)];
[self.layer setShadowColor:[[UIColor lightGrayColor] CGColor]];
[self.layer setShadowOpacity:0.5];
回答by Imanou Petit
Your code does not require the CGContextSetRGBFillColorcall and is missing the CGContextStrokeRectcall. With Swift 5, your final draw(_:)implementation should look like this:
您的代码不需要CGContextSetRGBFillColor调用并且缺少CGContextStrokeRect调用。使用 Swift 5，您的最终draw(_:)实现应如下所示：
class CustomView: UIView {
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = .white
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func draw(_ rect: CGRect) {
guard let ctx = UIGraphicsGetCurrentContext() else { return }
ctx.setStrokeColor(red: 0, green: 0, blue: 0, alpha: 0.5)
let rectangle = CGRect(x: 0, y: 100, width: 320, height: 100)
ctx.stroke(rectangle)
}
}
As an alternative, if your really want to call CGContextSetRGBFillColor, you also to have call CGContextFillRect. Your final draw(_:)implementation would then look like this with Swift 3:
作为替代方案，如果您真的想拨打CGContextSetRGBFillColor，您也可以拨打CGContextFillRect。draw(_:)使用 Swift 3，您的最终实现将如下所示：
class CustomView: UIView {
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = .white
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func draw(_ rect: CGRect) {
guard let ctx = UIGraphicsGetCurrentContext() else { return }
ctx.setFillColor(red: 1, green: 1, blue: 1, alpha: 0)
ctx.setStrokeColor(red: 0, green: 0, blue: 0, alpha: 0.5)
let rectangle = CGRect(x: 0, y: 100, width: 320, height: 100)
ctx.fill(rectangle)
ctx.stroke(rectangle)
}
}
回答by Fattie
One handy tip ......
一个方便的提示......
Very often, when you need to draw a square
很多时候，当你需要画一个正方形时
it's easier to just draw a 'thick stripe'.....
只画一条“粗条纹”会更容易......
let context = UIGraphicsGetCurrentContext()
context!.setLineWidth(100)
context!.setStrokeColor(blah.cgColor)
context?.move(to: CGPoint(x: 500, y: 200))
context?.addLine(to: CGPoint(x: 500, y: 300))
context!.strokePath()
That will draw a square, which runs downwards from 200 to 300.
这将绘制一个正方形，它从 200 向下延伸到 300。
It's centered on 500 across, and is 100 wide.
它以 500 为中心，宽度为 100。
回答by Madhu
CGRect bounds = connectorRect;
CGFloat minx = CGRectGetMinX(bounds), midx = CGRectGetMidX(bounds), maxx = CGRectGetMaxX(bounds);
CGFloat miny = CGRectGetMinY(bounds), maxy = CGRectGetMaxY(bounds);
CGContextSetFillColorWithColor(context, [UIColor grayColor].CGColor);
CGContextSetLineWidth(context, 1.0);
CGContextBeginPath(context);
CGContextSetStrokeColorWithColor(context,[UIColor clearColor].CGColor);
CGContextMoveToPoint(context, minx, maxy);
CGContextAddLineToPoint(context, midx, miny);
CGContextAddLineToPoint(context, maxx, maxy);
CGContextClosePath(context);
CGContextDrawPath(context, kCGPathFillStroke);
